//
// Created by sht on 2025/4/11.
//
#include <iostream>
using namespace std;
int main()
{
    // 请在此输入您的代码
    int n;
    cin >> n;
    int i = 1;
    int sum = 0;
    while(1)
    {
        for(int j = i; j >=1;--j)
        {
            ++sum;
        }
        if(sum >= n)
        {
            break;
        }
        ++i;
    }
    cout << i << endl;;
    return 0;
}